1. Field of the Invention
The present invention relates to a technique of manufacturing a compound thin film, more specifically, a method of depositing a nitrogen-containing compound thin film on a substrate, and an apparatus of manufacturing the same.
2. Description of the Related Art
Conventionally, it is difficult to grow a nitrogen compound in a vacuum, or to dope nitrogen into a semiconductor thin film during growth thereof, because nitrogen and nitrogen compounds are chemically stable and rarely react with the growing surface of the thin film during the growth. Consequently, it is difficult to obtain a p-type conductor by doping nitrogen into a II-VI Group compound semiconductor.
A II-VI Group compound semiconductor made of a group II device such as Cd or Zn, and a group VI device such as S or Se, is a good material for manufacturing a light emitting device. In the case of ZnSe, for example, doping nitrogen into the compound is known to be effective to make an acceptor. However, even if nitrogen gas or ammonia gas is introduced during molecular beam epitaxial growth (MBE) of ZnSe, hardly any nitrogen is absorbed into the film, because of the low reactivity of each of the gases. Consequently, with the conventional technique, it is not possible to make an acceptor so good as to achieve a sufficient p-type conductivity (see J. Appl. Phys., vol.58, pp1047-1049).
As described, conventionally, there is a drawback wherein nitrogen cannot be sufficiently absorbed into a compound film during growth thereof, because generally nitrogen and nitrogen compounds are chemically stable. In particular, although nitrogen is doped into a compound to achieve a p-type conductivity, it is difficult to carry out sufficient doping in the case of an II-VI Group compound semiconductor, in particular. Therefore, it is difficult to make a good p-n junction.